Abstract

Contrasting the properties of conscious and unconscious processes is crucial for understanding how consciousness occurs in the brain. In this chapter, we review the theoretical framework and empirical methods used to delineate and contrast conscious vs. unconscious perception. After outlining the main approaches to measure unconscious influences on brain and behavior, we describe some of the psychophysical tools employed to render stimuli unconscious, including the depletion of sensory signals, attentional resources, and vigilance states. We then provide an overview of the extent and limits of unconscious perception, and conclude on the future of the contrastive approach to the study of consciousness.